 /*
  * $Header: /cvshome/build/org.osgi.service.condpermadmin/src/org/osgi/service/condpermadmin/ConditionInfo.java,v 1.13 2006/06/16 16:31:37 hargrave Exp $
  *
  * Copyright (c) OSGi Alliance (2004, 2006). All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package org.osgi.service.condpermadmin;

 import java.util.ArrayList ;

 /**
  * Condition representation used by the Conditional Permission Admin service.
  *
  * <p>
  * This class encapsulates two pieces of information: a Condition <i>type</i>
  * (class name), which must implement <code>Condition</code>, and the
  * arguments passed to its constructor.
  *
  * <p>
  * In order for a Condition represented by a <code>ConditionInfo</code> to be
  * instantiated and considered during a permission check, its Condition class
  * must be available from the system classpath.
  *
  * <p>
  * The Condition class must either:
  * <ul>
  * <li>Declare a public static <code>getCondition</code> method that takes a
  * <code>Bundle</code> object and a <code>ConditionInfo</code> object as
  * arguments. That method must return an object that implements the
  * <code>Condition</code> interface.</li>
  * <li>Implement the <code>Condition</code> interface and define a public
  * constructor that takes a <code>Bundle</code> object and a
  * <code>ConditionInfo</code> object as arguments.
  * </ul>
  *
  * @version $Revision: 1.13 $
  */
 public class ConditionInfo {
     private String type;
     private String [] args;

     /**
      * Constructs a <code>ConditionInfo</code> from the specified type and
      * args.
      *
      * @param type The fully qualified class name of the Condition represented
      * by this <code>ConditionInfo</code>.
      * @param args The arguments for the Condition. These arguments are
      * available to the newly created Condition by calling the
      * {@link #getArgs()} method.
      * @throws java.lang.NullPointerException If <code>type</code> is
      * <code>null</code>.
      */
     public ConditionInfo(String type, String [] args) {
         this.type = type;
         this.args = args != null ? args : new String [0];
         if (type == null) {
             throw new NullPointerException ("type is null");
         }
     }

     /**
      * Constructs a <code>ConditionInfo</code> object from the specified
      * encoded <code>ConditionInfo</code> string. White space in the encoded
      * <code>ConditionInfo</code> string is ignored.
      *
      * @param encodedCondition The encoded <code>ConditionInfo</code>.
      * @see #getEncoded
      * @throws java.lang.IllegalArgumentException If the
      * <code>encodedCondition</code> is not properly formatted.
      */
     public ConditionInfo(String encodedCondition) {
         if (encodedCondition == null) {
             throw new NullPointerException ("missing encoded condition");
         }
         if (encodedCondition.length() == 0) {
             throw new IllegalArgumentException ("empty encoded condition");
         }
         try {
             char[] encoded = encodedCondition.toCharArray();
             int length = encoded.length;
             int pos = 0;

             /* skip whitespace */
             while (Character.isWhitespace(encoded[pos])) {
                 pos++;
             }

             /* the first character must be '[' */
             if (encoded[pos] != '[') {
                 throw new IllegalArgumentException ("expecting open bracket");
             }
             pos++;

             /* skip whitespace */
             while (Character.isWhitespace(encoded[pos])) {
                 pos++;
             }

             /* type is not quoted or encoded */
             int begin = pos;
             while (!Character.isWhitespace(encoded[pos])
                     && (encoded[pos] != ']')) {
                 pos++;
             }
             if (pos == begin || encoded[begin] == '"') {
                 throw new IllegalArgumentException ("expecting type");
             }
             this.type = new String (encoded, begin, pos - begin);

             /* skip whitespace */
             while (Character.isWhitespace(encoded[pos])) {
                 pos++;
             }

             /* type may be followed by args which are quoted and encoded */
             ArrayList argsList = new ArrayList ();
             while (encoded[pos] == '"') {
                 pos++;
                 begin = pos;
                 while (encoded[pos] != '"') {
                     if (encoded[pos] == '\\') {
                         pos++;
                     }
                     pos++;
                 }
                 argsList.add(unescapeString(encoded, begin, pos));
                 pos++;

                 if (Character.isWhitespace(encoded[pos])) {
                     /* skip whitespace */
                     while (Character.isWhitespace(encoded[pos])) {
                         pos++;
                     }
                 }
             }
             this.args = (String []) argsList
                     .toArray(new String [argsList.size()]);

             /* the final character must be ']' */
             char c = encoded[pos];
             pos++;
             while ((pos < length) && Character.isWhitespace(encoded[pos])) {
                 pos++;
             }
             if ((c != ']') || (pos != length)) {
                 throw new IllegalArgumentException ("expecting close bracket");
             }
         }
         catch (ArrayIndexOutOfBoundsException e) {
             throw new IllegalArgumentException ("parsing terminated abruptly");
         }
     }

     /**
      * Returns the string encoding of this <code>ConditionInfo</code> in a
      * form suitable for restoring this <code>ConditionInfo</code>.
      *
      * <p>
      * The encoding format is:
      *
      * <pre>
      * [type &quot;arg0&quot; &quot;arg1&quot; ...]
      * </pre>
      *
      * where <i>argN</i> are strings that are encoded for proper parsing.
      * Specifically, the <code>"</code>, <code>\</code>, carriage return,
      * and linefeed characters are escaped using <code>\"</code>,
      * <code>\\</code>, <code>\r</code>, and <code>\n</code>,
      * respectively.
      *
      * <p>
      * The encoded string contains no leading or trailing whitespace characters.
      * A single space character is used between type and "<i>arg0</i>" and
      * between the arguments.
      *
      * @return The string encoding of this <code>ConditionInfo</code>.
      */
     public final String getEncoded() {
         StringBuffer output = new StringBuffer ();
         output.append('[');
         output.append(type);

         for (int i = 0; i < args.length; i++) {
             output.append(" \"");
             escapeString(args[i], output);
             output.append('\"');
         }

         output.append(']');

         return output.toString();
     }

     /**
      * Returns the string representation of this <code>ConditionInfo</code>.
      * The string is created by calling the <code>getEncoded</code> method on
      * this <code>ConditionInfo</code>.
      *
      * @return The string representation of this <code>ConditionInfo</code>.
      */
     public String toString() {
         return getEncoded();
     }

     /**
      * Returns the fully qualified class name of the condition represented by
      * this <code>ConditionInfo</code>.
      *
      * @return The fully qualified class name of the condition represented by
      * this <code>ConditionInfo</code>.
      */
     public final String getType() {
         return type;
     }

     /**
      * Returns arguments of this <code>ConditionInfo</code>.
      *
      * @return The arguments of this <code>ConditionInfo</code>. An empty
      * array is returned if the <code>ConditionInfo</code> has no
      * arguments.
      */
     public final String [] getArgs() {
         return args;
     }

     /**
      * Determines the equality of two <code>ConditionInfo</code> objects.
      *
      * This method checks that specified object has the same type and args as
      * this <code>ConditionInfo</code> object.
      *
      * @param obj The object to test for equality with this
      * <code>ConditionInfo</code> object.
      * @return <code>true</code> if <code>obj</code> is a
      * <code>ConditionInfo</code>, and has the same type and args as
      * this <code>ConditionInfo</code> object; <code>false</code>
      * otherwise.
      */
     public boolean equals(Object obj) {
         if (obj == this) {
             return true;
         }

         if (!(obj instanceof ConditionInfo)) {
             return false;
         }

         ConditionInfo other = (ConditionInfo) obj;

         if (!type.equals(other.type) || args.length != other.args.length)
             return false;

         for (int i = 0; i < args.length; i++) {
             if (!args[i].equals(other.args[i]))
                 return false;
         }
         return true;
     }

     /**
      * Returns the hash code value for this object.
      *
      * @return A hash code value for this object.
      */

     public int hashCode() {
         int hash = type.hashCode();

         for (int i = 0; i < args.length; i++) {
             hash ^= args[i].hashCode();
         }
         return hash;
     }

     /**
      * This escapes the quotes, backslashes, \n, and \r in the string using a
      * backslash and appends the newly escaped string to a StringBuffer.
      */
     private static void escapeString(String str, StringBuffer output) {
         int len = str.length();
         for (int i = 0; i < len; i++) {
             char c = str.charAt(i);
             switch (c) {
                 case '"' :
                 case '\\' :
                     output.append('\\');
                     output.append(c);
                     break;
                 case '\r' :
                     output.append("\\r");
                     break;
                 case '\n' :
                     output.append("\\n");
                     break;
                 default :
                     output.append(c);
                     break;
             }
         }
     }

     /**
      * Takes an encoded character array and decodes it into a new String.
      */
     private static String unescapeString(char[] str, int begin, int end) {
         StringBuffer output = new StringBuffer (end - begin);
         for (int i = begin; i < end; i++) {
             char c = str[i];
             if (c == '\\') {
                 i++;
                 if (i < end) {
                     c = str[i];
                     switch (c) {
                         case '"' :
                         case '\\' :
                             break;
                         case 'r' :
                             c = '\r';
                             break;
                         case 'n' :
                             c = '\n';
                             break;
                         default :
                             c = '\\';
                             i--;
                             break;
                     }
                 }
             }
             output.append(c);
         }

         return output.toString();
     }
 }

